Textile process and product

ABSTRACT

PROCESSES FOR INCREASING THE STRENGTH OF WOVEN CELLULOSIC TEXTILE FABRICS COMPRISING STRETCHING ONE SET OF THE THREADS OF A MOIST FABRIC WHILE WUCH THREAS ARE IN A SUBSTANTIALLY STRAIGHT LINE (THAT IS, THEY AR NOT IN A WAVE-LIKE CONFIGURA TION), DRYING THE FABRIC WHILE IT IS SO STRETCHED, TREATING THE FABRIC WITH A CROSS-LINGING AGENT, EITHER BEFORE OR AFTER THE STRETCHING, AND SUBSEQUENTLY CURING THE CROSS-LINKING AGENT AFTER SAID DRYING, TOGHETHER WITH TEXTILE FABRICS SO OBTAINED.

United States Patent (3 3,568,280 TEXTILE PROCESS AND PRODUCT Ernst Weiss, Wattwil, Switzerland, assignor to Raduner & C0. AG., Horn, Switzerland No Drawing. Filed Aug. 5, 1966, Ser. No. 570,400 Claims priority, application Switzerland, Aug. 24, 1965, 11,891/65 Int. Cl. D06c 3/00, 3/08, 3/ 10 US. Cl. 28-76 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved textile process and product, and more particularly, it relates to a process for increasing the strength of cellulosic textiles and to the product obtained thereby.

It is known that the tensile strength of cotton fabrics is reduced to a greater or lesser extent by treatment with artificial resins, cross-linking with reactants such as N-substituted dimethylol urea compounds, dimethylol carbamates, aldehydes, and other chemical cross-linking agents for cellulose. Such a diminution in strength occurs even under conditions where there is no chemical damage to the fabric. It has been theorized that the reduction of tensile strength is caused by properties peculiar to the cellulose microstructure.

It has further been recognized that a tensile strength improvement may be obtained in cotton fabrics which have been impregnated With a precondensation product of an artificial resin or with a substance reactive with the cellulose by considerable stretching of the fabric prior to curing or the heat treatment necessary to accomplish the cross-linking. Generally however, the improvement in strength by such severe stretching treatment is not very effective. Since the improvements in strength, if any, are relatively small, such a process has not seen any important commercial use.

This invention provides a process for improving the mechanical strength of cellulosic textiles, especially those treated with cross-linking agents, and the superior stronger cellulosic textiles obtained by such a process.

Further and more specific objects, features, and advantages will clearly appear from the detailed description given below.

Briefly, the process of this invention involves subjecting the set of yarns or threads of a woven textile fabric the tensile strength of which is to be improved (warp or weft) to high tension while the yarns or threads are in a substantially straight configuration, that is the yarn or threads are not deformed to a wave-like or sinusoidal configuration by the action of the yarns or the threads of the other set of threads which cross them at right angles. Thus, the process of this invention can be carried out by submitting either the warp or the weft threads of a woven textile fabric to high tension. It has been surprisingly found that by the simple expedient of tensioning threads while they are in substantially straight lines a greatly improved strength can be obtained after the textile has been treated with cross-linking or resin-finishing agents.

Thus, a novel textile having improved physical properties, and particularly improved tensile strength, is obtained accordingto the process of this invention.

The process of this invention for increasing the strength of resin-treated textiles comprises stretching one set of the threads of a moist woven cellulosic textile fabric in a substantially straight line and drying the textile fabric while it is so stretched. The set of the threads which is stretched by high tension according to the process of this invention can be either the warp set or the weft set, but whichever set is stretched, there must be sufficient freedom for that set to assume a substantially straight configuration parallel to the direction of the imposition of the force if the superior results of this invention are to be achieved. The textile fabric is impregnated with a solution of a crosslinking agent either before or after the stretching. The cross-linking agent is then cured on the textile fabric by conventional methods of heating and the like. This process produces a novel cellulosic textile fabric having superior .tensile strength.

There has thus been outlined rather broadly the more important features of the invention in order that the detailed description hereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based can readily be utilized as a basis for the design of other processes for carrying out several purposes of the invention.

The process of this invention can be applied to all manner of woven fabrics containing cellulosic fiber material. It will be understood that the process of this invention can be applied to textiles consisting of natural or regenerated cellulose and cellulose derivatives, as well as blended fabrics containing such fiber types, and it is preferred to utilize the process for the treatment of textiles comprising natural cellulose, such as cotton or flax. Moreover, blended fabrics of cellulosic fibers with other natural fibers such as wool, silk and the like or artificial fibers such as nylon, polyester, and the like can be used.

The required stretching utilized in carrying out the process of this invention can be effected on the fabric after the fabric has been impregnated with a chemical cross-linking agent and while it is still moist. After stretching and drying, for example on a suitable tenter frame, the textile is then given a heat treatment in the usual manner to fix the cross-linking agent. It is also possible to combine the stretching operation with the drying step often effected after bleaching of the textile and before the textile is treated with the cross-linking agent. In this latter case, the textile must be returned to the same dimensions after the predrying step following impregnation with the chemical cross-linking agent as it had during the stretching operation.

The stretching of the textile is desirably effected in the direction in which it has the lower tensile strength. The process of this invention is especially suited for the improvement of cotton fabrics having a lower thread count in the weft direction than in the warp direction, as for instance cotton poplins. It is accordinglv preferred to exert the high tension in the Weft direction. The necessary straight-line configuration of the weft threads can be obtained by introducing the moist or impregnated fabric to be stretched in the weft direction into a tenter frame at a high overfeed, that is, at a higher introduction rate than take-off rate. The fabric is thus severely stretched, preferably to a width greater than that of the untreated raw fabric, and then dried in this condition. The amount of overfeed used is from about 5 to about 15%. The

finished width of the fabric, is desirably from about 3 to about 15% greater than the gray width, and it is preferred that the finished width of the textile fabric be from about to about greater than the gray width.

To carry out the process of this invention tenter frames 4 The following examples are given to illustrate the practice of this invention. The scope of the invention is defined in the appended claims.

EXAMPLE I can be used. Most suitable are pin tenter frames into 5 A Cotter} broadcloth having a y Width of with which the fabric is introduced at an angle, say 25 with 124 ellds/lhehr 001111? Ne 40/1, 67 PlekS/lneh, Count respect to the plane of the frame. In this manner, the Ne 4 1S mel'eeflled, bleached 1n the l l manner, fabric is contracted in the warp direction, and this makes h drled on a tehtel: ffame- Th the fabfle ip 'i it possible to maintain the .Weft threads in a Straight 10 with an aqueous solution containing 220 g./l. of Knittex line while they are being stretched. Moreover, clip tenter h a mlXed preeohqehsate 0f dlmethylslethyleheure'jl' frames equipped at the forward end with a device for q tetremethylolmelamlhe e 9 e y PR, introducing the fabric under overfeed, for example two a Z1hc 111t rate catalyst- The plck'up of thls Solutlon on the rollers having engaging small grooves between which the mammal 1S fabric is passed and thereby laid in small plaits, are suitone Portlon, of the 1s predned a i able for carrying out the process of this invention. frame the usual mafmer F Y 1191-11131 tenslons m In those instances Where Strengthening of the warp both the length and filling directions with the frame adthreads is desired, this can be carried out by considerable lusted to a wld'Eh of 91 stretching of the fabric in the longitudinal direction. For P 0f h f l B, is pretreated on this purpose a pair of introduction rollers running at f same frame but 15 Introduced Pm chains a higher Speed for example between 6 and 8% higher, w th a maximum overfeed and a stretching in the filling than that of the padding device in which the fabric is dmectlon Thereafter both.portlons A 5 B treated with chemical cross-linking agent can be placed of the fabnca are cilred for mmutes at between such padding device and the tenter frame. Such Washed at 60 with Solutlon of 1 of sioda ash rollers are preferably placed just in front of the tenter and 1 fatty. alcohol i and finally mused to frame neutrality and dried under tension on a tenter frame.

Chemicals which react with the cellulose by the forma- The results are as follows: tion of cross-linkages at elevated temperatures 'with or without the addition of an acid or all aline catalyst are Tensile Tearing suitable for use as chemical cross-linking agents for the str ngt st gt y cellulose in the practice of this invention. Desirably, so 59331,? fififi 552 1 called reactants i.e. materials which react with the Material E degrees hydroxy groups of the cellulose by the formation of G yfabric 25,1 cross-linkages are the agents used in the practice of P0rtionA qtthefa o this invention. Examples of such reactants are acetals figgff g fi fi gfggfigf fififi55 714 129 such as the reaction products of formaldehyde and dihigh tension 11024 128 ethylene glycol; dimethylol monocarbamates, such as 1 Average of rp and width. dimethylol methyl carbamate; cyclic dimethylol urea f ig f g f zi l g i ig iomlpounds teihylene 4.0 The foregoing table demonstrates the remarkable iny y pr py ene urea nazonels crease in the tensile and tearing strengths of the textile such as 1,3 dimethylol-S-hydroxyethylene perhydrotri- 1n the filling direction. azone-2. Also resin-forming pre-condensates may be used such as dimethylol urea, methylol melamine compounds EXAMPLE H such as tetramethylol melamine or water soluble etherified A cotton poplin having a gray id h of 96 ith 46 methylol melamine materials. Other suitable cross-linking ends per cm. count Ne 40/1 d 26 i k per cm agents are epmfldes Such the ether of ithyh count Ne 30/ 1, is mercerized, bleached in the usual manehe glycol, p lf y pyrldlhlum. p fl of nor, and stretched in filling direction while moist after any ch lO rc ,methy1 f d1V 1nY1Su1fhe derlvatlves, excess water has been squeezed 01f. The fabric is then ezlrldlnyl) phosphlnic crude, and hexemethylene dlcthyl- 50 prestretched in the filling direction to 99.4 cm. under ehe urea- Moreover, aldehydes Such as formaldehyde, minimum lengthwise tension, stretched in the filling di- Y L and ghltaraldehyde are also Suitable has rection to 98.5 cm., and dried on a tenter frame. h found that yfh use of aldehydes the Stretched Thereafter, the fabric is padded with an aqueous solufabrics are less sensitive to variations of the dosage of i containing 100 L/l, of 37% formaldehyde, 20 g. hy n In the conditions of the curing than normal of zinc chloride catalyst, and 0.4 rn1./l. of concentrated fabrics which v not been stretched- According to the acetic acid. The pick-up of this solution on the material is Process of the invention, the diflicnlties previously The fabric is again stretched in the filling direction nected with the use of aldehydes as cross-linking agents on to 98.5 cm., dried at 6-5 C., cured for 3 minutes at a eommel'elel Scale can largely be overcome. 150 C., washed with an aqueous solution containing The Process of this invention Produces Cross-linking 0 0.5% acetic acid, rinsed with cold water, squeezed olf, agent-treated cellulosic textile fabrics which have conand dried under tension. siderably greater strength than conventional resin-finished A second portion of the same fabric is finished in the cellulosic textile fabrics. The products of this invention same manner, but omitting the filling direction prestretchare suitable for the usual uses to which textile fabrics ing with overfeed. are put and are markedly superior in many uses because The results of this treatment are shown in the folof their improved mechanical properties. lowing tabulation:

Tensile Tearing strength strength in fillin fill- Crease angle degrees ing direoing direc- Material tion, kg. tion, g. Dry Wet Gray fabric 23 Fabric treated Without prestretching 8.5 540 127 152 Fabric treated with prestretching 16. 3 770 151 1 Average of warp and filling.

EXAMPLE in A cotton percale having a gray width of 102 cm. with 22ends/cm., count Ne 45/1, and 22 picks cm., ccunt Ne 67/1, is mercerized, bleached, and fed into the pin chains of a pin frame with a overfeed. The over feeding on the pin frame allows to stretch the fabric to 112 cm. in the filling direction, and the fabric is thereupon dried. The fabric is then padded with an aqueous solution containing 150 g./l. dimethylol propyleneurea and g./l. of zinc nitrate catalyst. The pick-up of the padding solution on the textile is 65%.

The fabric is then stretched in the filling direction to 112 cm., dried at 100 C., cured for 2.5 minutes at 160 C., washed in an aqueous solution containing 1 g./l. of soda ash and l g./l. fatty alcohol sulfate, rinsed with cold Water, and dried on a tenter frame.

When the textile treated according to the process of the present invention is compared with a second identical sample treated similarly, but without the prestretching in the filling direction, the following results are obtained:

A cotton warp satin having a gray width of 86 cm. with 65 ends/cm., count Ne 70/ 1 and 35 picks/cm., count Ne 90/1, is singed, desized, boiled off, mercerized under tension and bleached. The fabric is then introduced into the pin chains of a pin frame with 6% overfeed and then stretched to 89 cm. in the filling direction and dried in that condition.

The dried fabric is padded with an aqueous solution containing 190 mL/l. of a 50% solution of dimethylolmethyl carbamate, 28 g./l. of zinc chloride catalyst and 0.5 ml./l. of concentrated acetic acid. The pick-up of this aqueous solution is 60%.

The padded textile is then stretched in the filling direction to 89 cm. and dried at 80 C. The stretched and dried fabric is cured for 3 minutes at 150 C., washed at 60 C. with an aqueous solution of 1 g./l. of soda ash and 1 g./l. of fatty alcohol sulfate, rinsed with warm water and then with cold water, and finally dried under moderate tension.

The following results are obtained when this fabric is compared with an identical fabric similarly treated except for the prestretching in the filling direction:

Tensile Tearing strength strength in filling in filling Crease direction, direction, angle Material kg. g. degrees Gray fabric Fabric treated without prestretching in filling direction 4. 2 410 147 Fabric treated with prestretching in filling direction 9. 1 720 143 1 Average of warp and filling.

EXAMPLE V A cotton cretonne having a gray width of 86 cm. with 24 ends and picks/cm. "and a count Ne /1 is mercer- 6 iz'ed, bleached in the conventional manner, and dried on a tenter frame. Then the fabric is padded with an aqueous solution of g./l. of dihydroxyethylene urea and 16 g./l. of crystalline Zinc nitrate catalyst. The pick-up of this aqueous solution is 62%.

A first portion, A, of this fabric is dried under normal tension at 100 C. and a second portion, B, is introduced into the pin chain of a pin frame with an overfeed of 14% and thereby stretched to 96 cm. in the filling direction. Then, this B portion is also dried at 100%.

Both portions A and B of the textile are cured for 3 minutes at C., and then washed, rinsed and dried as described in Example IV.

When the two portions of the fabric are tested, the results tabulated below are obtained:

Gray fabric 18. 9 Finished fabric portion A 8. 8 Finished fabric portion B" 15. 7 896 114 Crease angle degrees 1 Average of warp and filling.

What is claimed is:

1. A process for increasing the strength of woven textile fabrics containing cross-linked cellulosic fibers which comprises stretching one set of the threads of a moist cellulosic textile fabric while said set is in a substantially straight line configuration, drying the textile while it is so stretched, and treating the textile fabric with a cross-linking agent, the stretching and drying being effected prior to cross-linking wherein the other threads, which cross the said set at right angles, are introduced into the stretching zone with maximum overfeed.

2. The process of claim 1 wherein the threads are stretched by an amount of from 3 to 15% of their original length.

3. The process of claim 1v wherein the threads are stretched by an amount of from 5 to 10% of their original length.

4. The process of claim 1 wherein the textile fabric is impregnated with a chemical cross-linking agent prior to the stretching.

5. The process of claim 1 wherein the stretching is carried out after the textile fabric has been bleached.

6. The process of claim 1 wherein the stretching is effected by introducing the moist textile fabric into a tenter frame under high overfeed to tension the textile in the weft direction.

7. The process of claim 6 wherein the fabric is introduced into a pin tenter frame with an inclination angle between about 20 and 30.

8. The process of claim 6 wherein the stretching is effected by introducing the textile fabric into a clip tenter frame by a means which overfeeds the fabric to the frame.

9. The process of claim 8 wherein the textile is introduced into the clip tenter frame by means of tWo rollers with engaging small grooves between which the fabric is passed.

10. The process of claim 1 wherein the moist textile fabric is prestretched by means of two pairs of delivery rollers the second pair being placed in front of a tenter frame and running at a higher speed than the first pair References Cited UNITED STATES PATENTS Davis et a1. 28 76'ELAST Cluett 161 -75X l0 Burgeni 161--172X McElrath .1. 161--75X 8 OTH R REFERENCES Hersh et al. The Eifect of Tension on The Properties of Resin-Treated Cotton Fabrics-Textile Research JournalApril 1962--V0l. 32, N0. 4Pages 271-284.

HERBERT B. GUYNN, Primary Examiner M. HALPERN,'Assistant Examiner U.S. C1. X.R. 8116; 2657 I 

